Tattooed ex-Marine who killed 12 people in country music bar massacre had PTSD: Gunman, 28, 'terrified' his mother and neighbors after returning from Afghanistan tour before he opened fire on student night

Ian Long, 28, opened fire at Borderline Bar and Grill in Thousand Oaks at 11.20pm on Wednesday night

He was dressed in all-black and used a legally owned .45 caliber handgun which had an extended magazine

Witnesses said he also let off smoke grenades inside to confuse the terrified crowds as they ran for their lives

In April, police and mental health specialists were called to Long's home after neighbors heard crashes coming from inside

They decided he was not qualified to be committed involuntarily and left him at home with his mother

Neighbors told DailyMail.com on Thursday that she lived 'in fear' he was going to harm himself

Long served in the Marines for five years between 2008 and 2013 during which time he was given 10 medals and toured Afghanistan

After leaving the Marines, he spent three years studying athletic training at California State University Northridge but he dropped out in 2016

A college roommate of his said he was 'mean', a 'loner' and would often dance in their garage alone

He killed himself on Wednesday in an office in the bar after killing 11 patrons and a sheriff's sergeant who responded

By Jennifer Smith For Dailymail.com and Ryan Parry West Coast Editor For Dailymail.com and Connor Boyd For Dailymail.com

The gunman who massacred 12 people at a country music bar in southern California on Wednesday night has been identified as a highly decorated ex-Marine whose neighbors say he was plagued with PTSD and terrified his own mother.

Ian Long, 28, opened fire on the Borderline Bar and Grill in Thousand Oaks at 11.20pm on Wednesday night during its weekly College Country Night where students from nearby schools line dance and listen to music.

He used a Glock .45 which had an extended magazine to kill 11 people inside the bar including 22-year-old Cody Koffman after opening fire on the bouncer and throwing smoke grenades among the crowds to confuse them as they tried to flee.

Long then shot a sheriff's sergeant who was one of the first on the scene. The 54-year-old sergeant, Ron Helus, died in the hospital afterwards.

Before SWAT teams entered the building, Long took his own life in an office inside. He used a legally purchased .45 caliber handgun to carry out the attack and had modified its magazine so it could hold more rounds.